This application claims benefit of Japanese Application No. 2001-237075 filed on Aug. 3, 2001, the contents of which are incorporated by this reference.
The present invention relates to an endoscope device, which can obtain a general-light image and a polarized-light image using polarized light.
As a first example of the related art, there is the U.S. Pat. No. 6,091,984. The example of the related art discloses a method for determining a property of living-body tissue by irradiating light to the tissue and analyzing the spectrum of the scattered light to extract a component, which is varied depending on the size of a nucleus of a cell.
More specifically, the spectrum scattered from the living-body tissue and the spectrum scattered by the background in a model in consideration with the thickness of the tissue and blood absorption are calculated to produce the ratio. The ratio is compared with the Mie scattering theory, and the size of cell nucleus is estimated. Here, one having a larger cell nucleus is an abnormal tissue of HGD (High Grade Dysplasia), an early cancer, or the like.
In addition, as a second example of the related art, there is PCT Publication WO 00/42912.
The HGD, an early cancer or the like occurs near a surface of living-body tissue. Then, a method is disclosed for determining a property of living-body tissue wherein scattered light from the tissue surface is extracted by using polarized light, and the spectrum is analyzed. In this publication, a device shown in FIG. 1A is disclosed. Notably, FIG. 1A is cited from IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS VOL. 5, NO. 4, pp. 1019-1026, by the same inventor.
In a device 130 shown in FIG. 1A, white light from a wide-band light source 131 is conducted by a fiber 132 and is converted to specific linear polarized light through a lens 133, an aperture 134 and a polarizer 135. Then, the light is entered to a beam splitter 136. The light reflected by the beam splitter 136 is irradiated to living-body tissue 137.
The light is scattered by the living-body tissue 137. The scattered light incident on the beam splitter 136, which is transparent partially, is reflected by a mirror 139 through the aperture 138 and is entered to a polarizing beam splitter 140.
A light component in a polarizing direction parallel to the direction polarized by the polarizer 135 of the light incident on the polarizing beam splitter 140 passes through the polarizing beam splitter 140 and is conducted to a multi-channel spectroscope 142 through a lens 141a. 
A light component in a direction orthogonal to the polarizing direction by the polarizer 135 is reflected by the polarizing beam splitter 140 and is conducted to the spectroscope 142 through a lens 141b. 
In this case, in order to prevent the reflected right from entering to the spectroscope 142 directly, the polarizing beam splitter 136 is disposed such that the illuminating light is inclined slightly with respect to the living-body tissue 137.
The parallel and vertical components are entered to spectroscope 142 by the polarizing beam splitter 140, and the difference is produced after the background correction (processing for calculating a ratio with respect to a scattering body of white light).
With this construction, light having a specific polarized component is irradiated to the living-body tissue 137. The scattered light is divided into a parallel polarized component and a vertical polarized component with respect to the polarized component of the illuminating light. Thus, the spectrum is detected. Here, the polarized component is stored in the scattered light returned from the surface of the living-body tissue 137 and becomes the polarized component parallel to the irradiated light.
Furthermore, the scattered light returned from the depths of the living-body tissue 137 is scattered strongly. Thus, the parallel component and the vertical component with respect to the irradiated light are substantially equivalent. In other words, the scattered light having parallel polarized light includes components from the surface of the living-body tissue 137 and the depths of the living-body tissue 137. The scattered light having vertical polarized light includes the component from the depths of the living-body tissue 137.
Here, by differentiating the scattered light having the parallel polarized light and the scattered light having the vertical polarized light, only scattered light on the surface of the living-body tissue 137 can be extracted. Furthermore, like the U.S. Pat. No. 6,091,984, the spectrum of the scattered light from the surface of the living-body tissue 137 is analyzed, and then the size of a cell nucleus is estimated. An advantage of this method is to allow extracting scattered light including much information relating to the size of the nucleus with good S/N by using polarized light.
FIG. 1B shows a spectrum of colon normal tissue while FIG. 1C shows a spectrum of tumor tissue. As shown in these FIGS. 1B and 1C, the strength of the scattered light increases at 600 to 650 nm once in the normal tissue. On the other hand, in the tumor tissue, the strength of the scattered light is reduced as the wavelength becomes longer. In addition, as a third example of the related art, there is A. Harris et al., xe2x80x9cThe Sturdy of the Microcirculation using Orthogonal Polarization Spectral Imaging, Yearbook of Intensive Care and Emergency Medicine 2000xe2x80x9d.
This example of the related art discloses a method for improving the contrast of a blood-vessel image by using polarized light.
More specifically, light having a specific polarized component is irradiated to tissue and the scattered light of a polarized component perpendicular to the polarized component of the illuminating light is made into an image. Here, the polarized component is stored in the scattered light returned from the tissue surface and becomes a polarized component parallel to the irradiated light. In addition, the scattered light returned from the tissue depths is strongly scattered. Thus, the parallel component and the vertical component with respected to the irradiated light are substantially equivalent.
In other words, by making into an image the light having the polarized light perpendicular to the polarizing direction of the illuminating light, the scattered light from the tissue depths can be made into an image. Thus, the scattered light from the tissue surface is reduced, as if the light were seen transparently from the depths of the tissue. As a result, the contrast of the blood vessel of the tissue surface can be improved. By using the above-described principle, a sclerotic endoscope has been developed.
In the first and the second examples of the related art, one polarized component is detected and is analyzed. Thus, image making is not described.
The third example of the related art makes into an image the light having a polarized component perpendicular to a polarizing direction of illuminating light. Thus, the light is not divided into the horizontal polarized component and the scattered light component for making an image. Furthermore, a construction for making both a general-light image and a polarized-light image is not disclosed.
It is an object of the present invention to provide an endoscope apparatus and an endoscope, which can obtain a polarized-light image by using polarized light in addition to obtain a general-light image.
It is another object of the present invention is to provide an endoscope apparatus and an endoscope, which can improve functionality of endoscope diagnoses, by including: a light source device for generating general illuminating light for obtaining a general-light image and polarized image illuminating light having a plurality of wavelength bands for obtaining a polarized-light image; an endoscope having a light conducting member for conducting the general illuminating light and the polarized image illuminating light, a polarizing member for emitting polarized illuminating light, which is polarized through the light-conducting member, to a subject side, and an image pickup device for outputting a parallel image signal and a vertical image signal captured, in the light reflected by the subject side, by using a light component in a polarizing direction parallel to a polarizing direction by the polarizing member and a light component in a polarizing direction perpendicular to the polarizing direction by the polarizing member, respectively;
an image processing device for performing image processing on at least one of the parallel image signal and the vertical image signal so that a general-light image can be displayed in a display device and for performing image processing on the parallel image signal and the vertical image signal so that a polarized-light image can be displayed in the display device,
a general-light image and a polarized-light image can be obtained.